Plant protection using arbuscular mycorrhizal fungi

Download

Date

Author

Metadata

Abstract

The interaction between several species of arbuscular mycorrhizal fungi,
micropropagated strawberry plants and Phytophthora fragariae, the pathogen which
causes red stele disease of strawberry plants, was investigated. The optimum
temperature for germination of zoospore cysts of P. fragariae in vitro was found to be
15°C, and growth of the emerging germ tube was significantly orientated towards the
strawberry root tip. Cyst germination was reduced in the presence of a mycorrhizal
strawberry root. The method of inoculation of strawberry plants with P. fragariae and
assessment of the resulting disease affected the results and the conclusions drawn
from the experiments, depending on the virulence of the P. fragariae strain used and
the susceptibility of the strawberry cultivar. Elsanta was more susceptible to P.
fragariae than the cultivar Rhapsody. A low level o f colonisation of Elsanta with the
arbuscular mycorrhizal fungi Glomus mosseae, Glomus intraradices or Glomus
fistulosum resulted in a significantly greater amount of total phosphorus in plant
shoots compared to non-mycorrhizal plants, although further increases in the
percentage of root colonisation by the fungi had no effect on the plants. The presence
of these mycorrhizal fungi had no effect on disease due to subsequent inoculation of
the plants by P. fragariae. Increasing colonisation of Elsanta by Scutellospora nodosa
was correlated with a significant increase in plant size and additional phosphorus
uptake. However, these same plants exhibited greater levels o f disease due to the
following inoculation with P. fragariae. A low level of root colonisation of Elsanta by
Acaulospora scrobiculata caused significant increases in plant size and phosphorus
uptake up to a threshold level o f root colonisation beyond which further increases had
no affect on the plant. Examination of biochemical markers in the form o f isozyme
banding patterns extracted from spores of arbuscular mycorrhizal fungi was explored
to assess its potential for use in strain identification, and discussed in relation to other
available techniques. The results are discussed in relation to the utilisation of specific
strains o f arbuscular mycorrhizal fungi as inoculants of micropropagated strawberry
plants of particular cultivars with the potential to increase plant growth and reduce the
level of disease due to soil-borne plant pathogens.